Create Kth Smallest Element in a BST.cpp

Author: piyush6348

Kth Smallest Element in a BST.cpp

@@ -0,0 +1,27 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    int numNodes(TreeNode* root){
+        if(root==NULL)
+            return 0;
+        
+        return (numNodes(root->left)+numNodes(root->right)+1);
+    }
+    int kthSmallest(TreeNode* root, int k) {
+        int pos=numNodes(root->left);
+            if(pos==k-1)
+                return root->val;
+            if(pos<k)
+                return kthSmallest(root->right,k-pos-1);
+            else if(pos>=k)
+                return kthSmallest(root->left,k);
+    }
+};